Can a person be terminated while out on workers compensation, my employer is running FMLA concurrent with WC.

They are stating because FMLA is running concurrent with WC, they only have to hold the position for 12 weeks. After that they do not need to hold my job. I'm a long time employee with a good tract record, my sick bank is maxed out 165 days I can not accure any more I actually give days back.I have 20 days vacation on the books, no past written disapline.
This is something new they recently started running FMLA parralle to WC. My fear is I work construction and if I got hurt twice in a year they would release me. I have discussed this with them and they are very shy to comment.